A great many different powertrain systems are well-known and widely used. Mechanical, hydro-mechanical, electric, hybrids of these and still others have been the subject of engineering research and commercial production for many years. In a conventional powertrain architecture for mobile machines, a transmission is positioned functionally between an engine and a final drive. The transmission in general provides different gear ratios or continuously variable effective gear ratios between the engine and the final drive.
In a conventional mechanical automatic transmission a plurality of gear sets are coupled between input and output shafts of the transmission, and torque transfer through the transmission switches among the gear sets depending upon conditions. In a hydro-mechanical transmission, a hydraulic pump typically driven by way of engine power is coupled with and supplies fluid to a hydraulic motor that in turn applies torque to a final drive or individual wheels or tracks. Over the years, engineers have proposed a great many variations on these and other basic transmission types. Commonly owned U.S. Pat. No. 8,808,131 to Seipold et al. is directed to a Multi-Range Hydro-Mechanical Transmission. Seipold proposes a design where a continuously variable transmission has multiple planetary gear sets, and a variator drives a ring gear of one of the planetary gear sets. Clutches are coupled between output shafts of the transmission and drive gears.